a. Field of the Invention
The invention relates to a backlight module.
b. Description of the Related Art
Referring to FIG. 7, in a conventional backlight module 100, micro dots 106 are typically formed on a bottom surface 102c of a light guide plate 102 by screen printing. The distribution densities of micro dots 106 in different areas of the bottom surface 102c may distinct from each other to adjust output luminance and luminance uniformity. However, micro dots 106 formed by screen printing are highly diffusive and have low directionality of light. Therefore, a light beam emitted by the light source 104 is liable to be scattered and leaves the light guide plate 102 to result in light loss. Besides, the inferior directionality of light may cause great difficulty in local dimming to fail to further improve luminance uniformity and image contrast.
U.S. patent application publication No. 20040076396 discloses a surface light source device having a lamp cover, a light source and a light guide plate. Condensing elements including a lens array are formed on a light-emitting surface of the light guide plate, and directional light-scattering elements are formed on a bottom surface of the light guide plate. U.S. Pat. No. 7,108,415 discloses a liquid crystal display device, where multiple light-extracting dots are formed on a bottom surface of a light guide plate. Each of the light-extracting dots has an arc-shaped cross-section and is formed by ink-jet printing. Taiwan patent application publication No. 201015129 discloses a light guide plate having a main body and a material destructive to total-internal-reflection, and multiple lenticular lenses are formed on a surface of the main body of the light guide plate. Taiwan patent application publication No. 200732785 discloses convex-shaped micro structures formed on a light guide plate by ink-jet printing.